As a reactive sizing agent which is usable for paper industry, alkenylsuccinic anhydrides and ketene dimers are known ("Pulp and Chemistry and Chemical Technology" Third Edition, JOHN WILEY & SONS, Inc. NEW YORK (1981).
.alpha.-Olefin-maleic anhydride copolymers are also disclosed in Japanese Patent Publication No. 62-25798/1987.
As emulsifying agents, addition products of ethylene oxides to higher alcohols, alkylphenols, higher fatty acids or the like. (Oil chemistry, vol. 10, p.282 (1961) are usually used, and these addition products have free hydroxyl groups.
As a treating agent for sizing paper, an emulsifiable liquid which is obtained by mixing a sizing agent and an emulsifying agent and then by mixing the mixture and water is usable.
Accordingly, if a mixture of a sizing agent and an emulsifying agent has long shelf stability, it is conveniently usable for sizing paper. However, since the conventional emulsifying agent has free hydroxyl groups, there are problems that the emulsifying agent and the sizing agent are reacted and the sizing effect is lowered during the mixture is preserved.
Furthermore, since the conventional sizing agent has remarkable hydrophobic nature, it is required to emulsify the sizing agent with an emulsifying agent. The emulsifying agent has hydrophilic nature, so that the mixture of the sizing agent and the emulsifying agent often shows insufficient sizing effect.
An object of the present invention is to provide sizing agents which are easily emulsifiable by mixing water, which have excellent sizing effect, long shelf stability and little lowered sizing effect.
Another object of the present invention is to provide emulsifying agents which have long shelf stability even if the emulsifying agents are mixed with conventional alkenylsuccinic anhydrides or ketene dimers, and have little lowered sizing effect during the mixtures are preserved.